Neuropathology and Applied Neurobiology最新文献

Aim: Pilocytic astrocytomas (PA) in adults are rare and may be challenging to identify based only on histomorphology. Compared to their paediatric counterparts, they are reportedly molecularly more diverse and associated with a worse prognosis. We aimed to describe the characteristics of adult PAs more precisely by comprehensively profiling a series of 79 histologically diagnosed adult cases (≥18 years).

Methods: We performed global DNA methylation profiling and DNA and RNA panel sequencing, and integrated the results with clinical data. We further compared the molecular characteristics of adult and paediatric PAs that had a significant match to one of the established PA methylation classes in the Heidelberg brain tumour classifier.

Results: The mean age in our cohort was 33 years, and 43% of the tumours were located supratentorially. Based on methylation profiling, only 39% of the cases received a significant match to a PA methylation class. Sixteen per cent matched a different tumour type and 45% had a Heidelberg classifier score <0.9 with an affiliation to diverse established methylation classes in t-SNE analyses. Although the KIAA1549::BRAF fusion was found in 98% of paediatric PAs, this was true for only 27% of histologically defined and 55% of adult PAs defined by methylation profiling.

Conclusions: A particularly high fraction of adult tumours with histological features of PA do not match current PA methylation classes, indicating ambiguous histology and an urgent need for molecular profiling. Moreover, even in adult PAs with a match to a PA methylation class, the distribution of genetic drivers differs significantly from their paediatric counterparts (p<0.01).

Objective: Filipin complex is an autooxidation-prone fluorescent histochemical stain used in the diagnosis of Niemann-Pick Disease Type C (NP-C), a neurodegenerative lysosomal storage disorder. It is also widely used by researchers examining the distribution and accumulation of unesterified cholesterol in cell and animal models of neurodegenerative diseases including NP-C and Sanfilippo syndrome (mucopolysaccharidosis IIIA; MPS IIIA). Recently, it has been suggested to be useful in studying Alzheimer's and Huntington's disease. Given filipin's susceptibility to photobleaching, we sought to establish a quantitative biochemical method for free cholesterol measurement.

Methods: Brain tissue from mice with MPS IIIA was stained with filipin. Total and free cholesterol in brain homogenates was measured using a commercially available kit and a quantitative LC-MS/MS assay was developed. Gangliosides GM1, GM2 and GM3 were also quantified using LC-MS/MS.

Results: As anticipated, the MPS IIIA mouse brain displayed large numbers of filipin-positive intra-cytoplasmic inclusions, presumptively endo-lysosomes. Challenging the prevailing dogma, however, we found no difference in the amount of free cholesterol in MPS IIIA mouse brain homogenates cf. control tissue, using either the fluorometric kit or LC-MS/MS assay. Filipin has previously been reported to bind to GM1 ganglioside, however, this lipid does not accumulate in MPS IIIA cells/tissues. Using a fluorometric assay, we demonstrate for the first time that filipin cross-reacts with both GM2 and GM3 gangliosides, explaining the filipin-reactive inclusions observed in MPS IIIA brain cells.

Conclusion: Filipin is not specific for free cholesterol, and positive staining in any setting should be interpreted with caution.

Pediatric anesthesia is a diverse subspecialty practiced at thousands of hospitals and ambulatory surgery centers across the country. Most unusual and high-risk cases are performed in dedicated children's hospitals. However, the majority of cases and practitioners are based in the community. We present a review of demographics in pediatric anesthesia in the United States across 7 years of data from US Anesthesia Partners, a national anesthesia practice, which covers the full range of hospitals and outpatient facilities.

Aim: Amyotrophic lateral sclerosis (ALS) is a heterogeneous neurodegenerative disease with limited therapeutic options. A key factor limiting the development of effective therapeutics is the lack of disease biomarkers. We sought to assess whether biomarkers for diagnosis, prognosis or cohort stratification could be identified by RNA sequencing (RNA-seq) of ALS patient peripheral blood.

Methods: Whole blood RNA-seq data were generated for 96 Australian sporadic ALS (sALS) cases and 48 healthy controls (NCBI GEO accession GSE234297). Differences in sALS-control gene expression, transcript usage and predicted leukocyte proportions were assessed, with pathway analysis used to predict the activity state of biological processes. Weighted Gene Co-expression Network Analysis (WGCNA) and machine learning algorithms were applied to search for diagnostic and prognostic gene expression patterns. Unsupervised clustering analysis was employed to determine whether sALS patient subgroups could be detected.

Results: Two hundred and forty-five differentially expressed genes were identified in sALS patients relative to controls, with enrichment of immune, metabolic and stress-related pathways. sALS patients also demonstrated switches in transcript usage across a small set of genes. We established a classification model that distinguished sALS patients from controls with an accuracy of 78% (sensitivity: 79%, specificity: 75%) using the expression of 20 genes. Clustering analysis identified four patient subgroups with gene expression signatures and immune cell proportions reflective of distinct peripheral effects.

Conclusions: Our findings suggest that peripheral blood RNA-seq can identify diagnostic biomarkers and distinguish molecular subtypes of sALS patients however, its prognostic value requires further investigation.